Design And Application Of Ethernet Ring Protocol For PIS System

Passenger information system,referred to as PIS,is an important part of the metro.Through the PIS system,passengers can get public-notice,real-time news,etc.Moreover,the driver can get real-time passergers' information better.In subway consists,PIS system includes three subsystem,they are Public Address System,CCTV Monitoring System,Information Display and Media player System.With the development of high definition technology,the vehicle PIS System requires a larger bandwidth,and Ethernet technology can support that.It is necessary to build a redundant Ethernet Network in PIS system.In the vehicle PIS system,the link aggregation and single ring network topology are usually used in Ethernet Switch for redundancy.According to the introduction of the ECN(Ethernet Consist Network)topology in the IEC61375-3-4 standard,it is pointed that the ladder ring topology has the highest redundancy level.In this thesis,an Ethernet Ring Protocol is designed for PIS system.It can not only support a single ring topology,but also a ladder ring topology.This protocol is designed and implemented base on Layer 2 Ethernet Switch platform.The main content of this thesis is as follows:(1)An Ethernet Ring Protocol is designed to support single ring network topology and ladder ring network topology;(2)Implement the Ethernet Ring Protocol on Layer 2 Ethernet Switch,and the recovery time is less than 50 ms.(3)The Ethernet Ring Protocol is applied in the PIS system.In this thesis,the Ethernet Ring Protocol designed and implemented is to support single ring topology network and ladder ring topology network.When some links are abnormal,the recovery time of the network is within 50 ms,which greatly improves the redundancy protection of the link layer of the system.This provides a more reliable Ethernet network for the PIS system.